Cellular slab



s sheets-sheet 1 CELLULAR SLAB P. E. KNUDSl-:N

Filed March 24, 1959 Feb. 9,1943.

. INVENTOR PERcrEK/vuasE/v L Y E N R O l fl A Y B P. E. KN'UDSEN CELLULAR SLAB Feb. 9, 1943.

Filed March 24, 1939 Sheeis-Sheet 2 ATTORNEY Feb. 9,'A 1943. P, E, KNUDSEN 2,310,442

CELLULAR SLAB Filed March 24, 1939 3 Sheets-,Sheet 5 'mwa/AL ATTORNEY Patented Feb. 9, 1943V CELLULAR SLAB Percy E. Knudsen, Pittsburgh. Pa., assigner to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation of Pennsylvania Application March 24, 1939, Serial No. 263,926

(CLM- 68)A 3 Claims.

The present invention relates` to structural slabs or blocks of cellular material suitable for use in the fabrication of buildings, and it has particular relation to the fabrication of slabs of cellular glass or glass-like materials.

One object of the invention is to provide a lightweight, thermallyl non-conductive and chemically-resistant slab capable of withstanding relatively high bending loadsv without breakage.

A second object of the invention is to provide a simple and convenient method of fabricating slabs of the foregoing type.

In the fabrication of walls, iloors and .roofs or similar shell portions of buildings, a common material has heretofore comprised concrete, i. e. a stone-like agglomerate of gravel, sand, and Portland cement. Such material is low in tensile .strength, is extremely heavy and dense, and

therefore slabs, possessing adequate resistance to breakage, under bending loads, must be comparatively heavy and massive. Accordingly, the

use of the slabs in buildings imposes heavy loads upon the supporting elements thereof. Furthermore, the heavy, dense bodies are relatively conductive to heat and unless specialmeans is provided for the insulation of the building fabricated from them, heat losses through the slabs is likely to be excessive.

In accordance with the provisions of the present invention portions of the shells of buildings such as walls, roofs and floors are formed of i of a building deck or wall constructed in accordance with the provisions of the present in- I vention.

Fig. 2 is a fragmentary sectional view substantially upon the line II--II of Fig. 1.

Fig. 3 illustrates a slightly modified form of' means .for mounting slabs. y y

Fig. 4 illustrates a method of formingv the slabs constituting' the subject matter of the invention.

Fig. 5 is a sectional viewof a roofing or flooring structure embodying blocks or slabs constituting the subject matter of the present invention and having protective coatings thereupon.A Fig. 6 is a sectional view illustrating acon-l the line IX-IX of Fig. 8.

Figs. 10 and 11 are sectional views illustrating' two methods of forming the slabs shown in Figs.

8 and 9.

In the drawings like numerals refer to like parts throughout.

A deck, such as a roof or floor constructedv in accordance with the provisions of the present invention as illustrated in Figs. 1 and 2 may comprise a series of panels or slabs l0 (preferably of square or rectangular outline) disposed in rows between structural beams, such as vrafters or joists. The latter elements, in the form shown, comprise bars of iron or other metal, or wood, which at their ends are supported by any suitable means (not shown). They may'be of inverted T cross-section and may include a vertical web'l2 and transverse flanges I3, that support the/slabs.

Tl1e slabs I0 comprise an appropriate frame I4 consisting of angle bars lll, which are welded or otherwise secured together at their extremities. One flange i6 is vertically disposed partially or completely to cover the edge of the slab and the other flange Il is inwardly directed to provide a bearing surface for the edge of thev slab. `Transversely-eirtending reinforcing rods l8r, plain or deformed, interconnect two opposed sides of the frame and are aixed thereto by welding or by other convenient means in order 'togprovide a grill, which, preferably as shown in Fig. 2, is disposed near the bottom of the slab.l

- These rods are of substantial size-usually oneeighth inch in diameter, or greater. The space within the frame and about the rods is filled with cellular glass, i. e. a. highly ceuulated g1ass having a density of less than 1 and having high resistance to conduction of heat. The preparation of the glass body will be described later.

The frame of the slab may be connectedor afxed to the supporting members I i in any suit- A able manner. In the form of the invention illustrated in Figs. 1 and 2,Y holes are formed in the ,webs I2 and pins i9 are inserted through' the.

openings and embedded in the cellular material within theframe.

A slightly modified means for securing the slabstotheraftersorbeamsisillustratedinl'ig. 3. Inthisconstructionholesareformedinthe webs 2l of supporting beams 22, corresponding tobeams Il andbolts 2l arethreadedintomating openings in the anges 24 of the frames 2l, of the panels 21. The space between the adjacent panels may be filled with sealing material such as mastic or a cement, indicated at 28.

A convenient method of forming the cellular glass body is illustrated in Fig. 4. Accordingto this method, the frame I4 is disposed with flange Il upon a slab 3l of refractory material, such as a high chromium steel, carborundum, ceramic material. or any other material having high medmnlcal strength, and beingcapable of withstanding high temperatures. In order 'to prevent adhesion of cellular glass to the slab, the latter may conveniently be powdered with or washed with a slip, comprising highly refractory substance, such as lime, magnesia, graphite, carbon black, or the like. 'l'he frame is then partially filled with an appropriate amount of a mixture of glass properly crushed, for example, to a particle size, such that most of it will nass a screen of approximately 75-100 mesh. The thickness of this layer may be about one-seventh that of the finished slab. This crushed glass is admixed with a suitable amount of a gassing agent, such as finely-divided calcium carbonate (preferably chemically precipitated calcium carbonate) of a grade similar to whiting. 'I'he amount of calcium carbonate is susceptible of variation, but

usually is within the limits of 1 to 2 per cent, e. g. about 11/2 per cent.

'IThe mixture of crushed glass and calcium carbonate is leveled oif and the slab with the frame disposed thereupon is slid into a conventional furnace 33, having a bottom 34 and a roof I5. Any convenient means may be employed to heat the mixture within the frame, but conventional gas burners 36 constitute an example of `such means. Within the furnace the mixture of crushed glass and gassing agent is heated to a temperature sufficient prelimi'narily to sinter the particles of glass together at their points of contact, but not to melt it down to a fluid mass. This usually occurs at a temperature of about 1200 or 1400 F. Heating is then continued to and somewhat above the temperature of decomposition of the gassing agent (calcium carbonate). temperature of about 1400 or 1500 F. 'I'he temperature is then further raised to about 1600 or 1800 F., but should not become so great as to effect complete fusion and blending of the particles of glass. As the gassing agent decomposes liberated carbon dioxide bubbles are formed in the mass and these expand to provide a thoroughly cellulated mass of desired thickness. When the expansion is complete, heating is discontinued and the bodies are gradually cooled to eifect 'I'he cellular mass thusobtained is extremely light in weight. In many cases the specic gravitymaybeaslowas or0.4 andishighly resistant to conduction of heat. Although it inherently is relatively weak in tension and therefore is'but poorly adapted to withstand bending stresses, the rods I8 embedded therein greatly increase the strength of the slab in tension. The joiningoftherodstothesides oftheframeassure that the tensional forces exerted upon the rod are transmitted to the sides of the frame and even though adhesion between the rods and ineglassisslightgreatstrength oftheslabis assured.

.It will be apparent that the slabs, by reason of their highly cellular structure, are somewhat poor in resistance to crushing forces. particularly if the latter are concentrated. Therefore. if these slabs are to be used as floors or even as roofs, it is sometimes desirable to provide more resistant surfaces. This may be accomplished by coating the slabs with a layer 31 of concrete, asphalt, or the like illustrated in Fig. 5. In this form of the invention it will be observed that the slabs are supported upon the same beams Il of T crosssection in connection with Figs. 1 and 2, already described, and are locked in position by pins II in holes, in webs I2.. In order to permit the insertion of pins II a portion Il, of the cellular glass adjacent to the opening may be chipped from the slab as indicated at 39. The notch thus formed is filled by the material forming the layer 31.

It is also possible to provide the cellular slab with a relatively dense hard surface layer 4l illustrated in Fig. 3. I`n order to form such layer frame 42 of angle irons may be inverted upon a slab 43, as illustrated in Fig. 6. A thin layer 44 of crushed glass containing not more than about l per cent ofcalcium carbonate is then superposed upon the slab and subsequently additional A crushed glass containing the proper amount of Such decomposition usually occurs at a f calcium carbonate for maximum cellulation is distributed over the crushed layer. When the slab is heated by burners 48 in the furnace 41 to the temperature requisite for its formation, the upper layers of crushed glass are sintered together and then strongly cellulated. However, but comparatively Slight cellulation occurs in the layer adjacent the supporting slab 43. When' the slab is removed from the furnace and annealed it is found to possess a strong rigid surface capable of bearing concentrated loads of considerable magnitude. However, the main body of the slab is adequately cellulated in order to obtain low weight of the body as a whole and to obtain adequate thermal insulation.

Fig. 7 illustrates a slightly modified form of frame for the slab in which the angle irons disclosed in Fig. l are replaced by channel irons 5l, the flanges 5I and 52 of which overlap the edges of the cellulated glass 53 upon both sides. This construction is somewhat stronger than a simple angle iron construction. Furthermore. all corners of the cellulated glass are enclosed and protected by the frame. Reinforcement Srltdt; 54 interconnect two opposed sides of the In Figs. 8 and 9 is shown a block or slab structure which is particularly suitable for use in the fabrication of vertical walls. In this embodiment of the invention reinforcing rods 6I are-embedded at suitable intervals in slabs 6I of cellulated glass formed by heating an appropriate mixture of crushed glass and calcium carbonate in a mold. The rods at one end, are provided with socket portions 02, having flanges or heads i3, which provide bearing surface for the rods upon the surface of the glass. It will also be observed that the rods include prolecting portions I4, which, when the blocks are laid, one upon top of the other, are adapted to project into the sockets of the rods in the adjacent course, thus positively tying the blocks together into a unitary construction. The joints between upon the slab.

blocks may be sealed with cement or mastic. If desired, rods of alternate blocks may be replaced, with tubes having an internal diameter sufficient to admit the projecting ends 64 of the rods of the adjacent blocks. The sockets on the rods may then be eliminated. Reinforcing wires are indicated at 65. Y

Two methods of forming the type of blocks illustrated in Figs, 8 and 9 are shown in Figs. 10 and ll. In the method shown in Fig. 10, a mold 66, comprising a bottom slab 61 and side walls 68, is formed of refractory material. At least one wall, e. g. 69 is movable'with respect to slab 61 and may comprise a flange 1I secured to the base by bolts. The movable wall is formed with openings 12 through which the adjacent extremities 64 of rods 60 loosely project. The socket portions 62 of the rod may be supported by pins 13 projecting inwardly from the opposite wall 68.

In the operation of the method, the sides 68 and 69 may be superposed upon slab 61 and the inner surfaces coated with a powder or slurry of lime, or other wash, to prevent adhesion of the block. The reinforcing rods` are then placed in position and a layer 14, of powdered glass, or blast furnace slag, admixed with a gassingagent, is spread to fdesiredthickness The mold is subsequently slid upon the bottom 16 of furnace 11 and heated by burners 18 to form a' coherent cellulated body, which is subsequently annealed. In order to remove the blocks from the mold, side 69 is first removed from portions 64 and the slabs are slid forwardly until sockets 62 clear pins 13, after whichthe block may be lifted bodily from the mold. V

In the method illustrated in Fig. 11a mold 80, of appropriate cross-section and of a height corresponding to blocks 6l, is superposed upon a slab 8| and the inner surfaces ofthe assembly are suitably washed with lime or other material to render the surfaces non-adhesive.

tubular I Rods 60 are properly placed in the molds with flanges 63 restingfllpn' the slab. YThe moldV is then filled to an appropriate depth (e. g. oneseventh its height), with crushed glass admixed witha gassing `agentand the assembly is 1nserted in furnace 62. Flames from burners 83 play upon the mold until the contents are sintered, and a coherent cellular block is formed. When the block has been removed from the furnace, annealed and cooled the mold may be forced or lifted oft therefrom. Fluid cellular the molds material may, also, be poured into directly and hardened by cooling.

,An important feature of the invention as herein disclosed consists in the fact that because of its peculiar nature, it is possible to embed rods of substantial size, e. g. ofa diameter of one-eighth or Jone-half inch, or even larger with cracking the glass. This, of course, would be impossible with ordinary glass.

The forms of the invention herein shown are to be considered merely as illustrative. It will be apparent that numerous modifications may be made therein without departure from the spirit of the invention or the scope of the appended claims.

i What I claim is:

1. A method of fabricating reinforced slabs of cellular glass which comprises disposing a frame of a contour corresponding to that of the desired cellular glass slab and having reinforcing rods interconnecting two opposed sides thereof, upon a slab providing a temporary mold bottom', partially filling the frame with a mixture of crushed glass and a gassing agent, heating the mixture to a temperature above that of sintering of the particles of glass and decomposition of the gassing agent, in order to form an expanded but coherent cellular body lling the frame and having the rods embedded therein, and further having a permanent frame disposed thereabout, then annealing the slab.

2. A block of cellular glass having reinforcing rods embedded therein, the rods at one end projecting beyond lthe edge of the block and having sockets at the other end to receive the projecting portions of the rods in the adjacent block, when the blocks are laid in the wall, the socket ends of said rods having flanges providing bearing surfaces upon the glass.

3. A composite slab-like building unit adapted to be laid in a reclining position and being capable of withstanding relatively high bending loads without breakage, comprising a layer of highly cellulated glass having low heat conductivity and low resistance to crushing forces, metallic reinforcements embedded inthe cellular layer near to the bottom of the slab, the reinforcements being attached to members disposed transversely thereof and providing a bearing upon the cellular material, the upper face of the layer of highly cellulated glass being bonded to a facing layer of relatively dense material having high resistance to crushing forces.

ERCY E. KNU'DSEN. 

